This invention relates to couplings used as pipe joints, and more particularly it relates to couplings for pipes having identical ends to be butted together. Since such pipes have no hubs, bells or spigots, the couplings are sometimes referred to as "no-hub" couplings.
Couplings of this general type are disclosed by Evans, U.S. Pat. No. 3,233,922, and by Schaub, U.S. Pat. No. 3,359,017. Both disclose a gasket or packing member which encircles the pipe (and eliminates the need for caulking), a corrugated shield having a lapped and a lapping end, two clamping bands attached to the shield along opposite edges and having inclined slots at one end and screw tightening elements at the other. The two disclosures differ in the shape and extent of the corrugations, and the number and position of the rivets used to attach the bands to the shield.
The stated purposes of the corrugations and separate bands are to equalize pressures and accommodate irregular pipes. I have determined that in the great majority of cases these are non-existent problems. More particularly, I have determined that perfectly satisfactory couplings can be made from an integral shield/band member. In this manner, the cost of the coupling is substantially reduced.